GMC Suburban: Which Version to Buy and Why
The GMC Suburban range in this catalogue presents a straightforward choice between two versions: 5.7 AT and 7.4 AT. Both belong to the same generation, produced from 1992 to 1999, and both combine an SUV 5-doors body with a 4-speed Automatic gearbox and AWD. Their kerb weight, gross weight, fuel-tank capacity, suspension, brakes, and basic engine layout are also identical in the available data.
The GMC Suburban range in this catalogue presents a straightforward choice between two versions: 5.7 AT and 7.4 AT. Both belong to the same generation, produced from 1992 to 1999, and both combine an SUV 5-doors body with a 4-speed Automatic gearbox and AWD. Their kerb weight, gross weight, fuel-tank capacity, suspension, brakes, and basic engine layout are also identical in the available data. The decision therefore comes down mainly to engine size and output. The 5.7 AT is the less powerful option, with 200 hp from 5,737 cc, while the 7.4 AT provides 230 hp and 515 Nm from 7,400 cc.
GMC Suburban generations and versions
The catalogue contains one generation of the GMC Suburban. This generation ran from 1992 to 1999, used an SUV 5-doors body, and included two versions: 5.7 AT and 7.4 AT. Because both versions share the same production period and listed chassis specifications, there is no generational change to compare. The meaningful comparison is between the two engines offered within this generation.
Engine specs comparison
| Version | Power | Torque | Displacement | Fuel | Cylinders | Layout | Boost | Gearbox | Drive |
|---|---|---|---|---|---|---|---|---|---|
| 5.7 AT | 200 hp / 147 kW | not measured | 5,737 cc | Gasoline | 8 | V-shaped | No | 4-speed Automatic | AWD |
| 7.4 AT | 230 hp / 169 kW | 515 Nm | 7,400 cc | Gasoline | 8 | V-shaped | No | 4-speed Automatic | AWD |
Both versions use a Gasoline, naturally aspirated 8-cylinder, V-shaped engine mounted Front, longitudinal. Neither has boost. The 7.4 AT adds 30 hp and 22 kW over the 5.7 AT, an increase of 15% in horsepower. It also adds 1,663 cc of displacement, which is approximately 29% more than the smaller engine.
The 5.7 AT produces approximately 34.9 hp per litre, while the 7.4 AT produces approximately 31.1 hp per litre. This means the 5.7 AT extracts about 3.8 more hp per litre from its displacement. The larger engine still delivers the greater absolute output, but its extra capacity produces a proportionally smaller increase in horsepower.
The database does not provide torque for the 5.7 AT, so a direct torque difference cannot be calculated. The 7.4 AT is listed at 515 Nm. Power and torque engine speeds are not measured for either version. Valves per cylinder and bore-and-stroke figures are not measured for the 5.7 AT; the 7.4 AT has 2 valves per cylinder and a bore and stroke of 108 × 101.6 mm.
Performance, mpg, and economy
Acceleration from 0–100 km/h is not measured for both 5.7 AT and 7.4 AT. Top speed is also not measured for either version. The available power figures show that the 7.4 AT has the stronger output, but the data does not establish how much faster it accelerates or whether it has a higher maximum speed.
City fuel consumption is not measured for the 5.7 AT and 7.4 AT. Highway fuel consumption is not measured for both versions, and combined fuel consumption is likewise not measured. Consequently, an mpg comparison cannot be supported by the catalogue data. The larger displacement of the 7.4 AT should not be used as a substitute for a measured economy figure.
CO₂ emissions are not measured for either version, and an emissions class is not measured for either one. Fuel grade is also not measured. Both versions carry a 150-litre fuel tank, so tank capacity does not distinguish them.
Dimensions, weight, and chassis specs
Full exterior dimensions are not measured for either version. Ground clearance is not measured, and wheel sizes are not measured for both the 5.7 AT and 7.4 AT.
The available weight figures are identical. Each version has a 2,300 kg kerb weight and a 3,250 kg gross weight. The difference between gross and kerb weight is 950 kg for both versions.
Their equal kerb weights make the power-to-weight comparison especially clear. The 5.7 AT carries approximately 11.5 kg per hp, while the 7.4 AT carries 10 kg per hp. Expressed another way, the 5.7 AT provides about 87 hp per tonne, compared with 100 hp per tonne for the 7.4 AT. On the supplied figures, the 7.4 AT therefore has the better power-to-weight ratio.
Chassis specifications do not separate the two versions. Both have Independent, torsion front suspension and Dependent, leaf spring rear suspension. Both use Disc front brakes and Disc rear brakes. Each version also combines a 4-speed Automatic gearbox with AWD.
Reliability and problems
Reliability ratings, failure records, service intervals, and model-specific problems are not measured in the supplied data. The specifications therefore do not support a claim that either the 5.7 AT or 7.4 AT is more reliable.
The shared gearbox, drive, suspension, brake, and weight specifications narrow the mechanical comparison, but they do not prove equal ownership costs or durability. Repair prices, parts prices, insurance costs, and purchase prices are also not measured, so they cannot be used to rank the two versions.
Which GMC Suburban version should you buy?
Choose the 5.7 AT if the smaller engine is your priority and 200 hp is sufficient for your needs. It gives up 30 hp to the 7.4 AT, but uses 1,663 cc less displacement and has the higher specific output at approximately 34.9 hp per litre. Its torque, acceleration, top speed, and fuel consumption are not measured, so the available data cannot establish whether it is the more economical or less capable choice in everyday driving.
Choose the 7.4 AT if you want the strongest documented output in this GMC Suburban generation. Its 230 hp is 15% above the 200 hp of the 5.7 AT, and it is the only version with a measured torque figure, at 515 Nm. Because both versions weigh 2,300 kg, the larger engine also improves the ratio from approximately 11.5 kg per hp to 10 kg per hp.
What the larger engine demonstrably buys is 30 hp, 22 kW, 1,663 cc of additional displacement, and a better power-to-weight figure. What it does not demonstrably buy—because the relevant values are not measured—is quicker acceleration, a higher top speed, or better performance under any specific driving condition. Fuel economy and price are also not measured, so there is no factual basis here for calculating the operating-cost or purchase-cost penalty of the 7.4 AT.
On specifications alone, the 7.4 AT is the stronger choice because it delivers more power at the same listed kerb weight and with the same Automatic, AWD, suspension, brake, and tank specifications. The 5.7 AT remains the logical alternative for a buyer who prefers the smaller-displacement version and does not require the additional 30 hp.